Screening and identification of antibiotic producing strains of Streptomyces

About 450 actinomycetes were isolated from nearly 100 soil samples collected from different parts of West Bengal. The isolates were screened on the basis of their inhibitory effect against test organisms. Finally two potent antibiotic producers were chosen having maximum inhibitory effect on both gram positive and gram negative test bacteria. On the basis of morphological, structural, physiological and biochemical characters, the two potent antibiotic producers were identified as Streptomyces violaceus-niger and S. antibioticus.